Resrearch Of DSP-based Digital Ultrasonic Peening Power Supply

Once the technique of improving the fatigue performance of welded joints by ultrasonic peening treatment (UPT) has been realized by this research group, it has been paid fully attention to. As for its advantages of handy equipment, little noise, high efficiency, low cost and energy saving, it has been one of the perfect post-weld treatments for improving the fatigue performance of the joints. However, its analog power supply has the shortage that cannot be overcome.Digital power supply can achieve flexible control, high stability and precision and fine interface compatibility. In order to solve the problem of real-time control and back adjustment of the analog power, in this paper, digital ultrasonic peening power supply whose control system is based on DSP (Digital Signal Processor) has been developed.At first, hardware circuit of the system has been designed, including minimum system of DSP, sampling pretreatment, dead zone formation, constant amplitude control and display circuit. According to the frequency of DSP and the requirement of control precision, frequency multiplier has been used to reduce to adjusting step size. In the software programming, control algorithm is improved according to the characteristic of ultrasonic peening machine. Optimal scan region is settled as well as the threshold of the current, so that it is easier for frequency track. The program includes A/D conversion, phase difference calculation, PWM formation, D/A conversion and numeral display.On-line testing shows that, this digital ultrasonic peening power supply based on DSP can make the system work at the resonance state, and the peening process is stable. Both the hardware and software can achieve the expected function.